Linear positive and negative magnetoresistance in topological insulator Bi_2Se_3 flakes

摘要

The linear positive magnetoresistance (MR) and negative MR are emerging as intriguing phenomena in topological materials. Here, we report the magnetotransport properties of topological insulator Bi2Se3 flakes with different thicknesses grown by chemical vapor deposition. A non-saturating positive MR is observed in the perpendicular fields (B perpendicular to I), while an evident negative MR is observed in the parallel fields (B//I). Both the positive MR and negative MR show a linear magnetic field dependence at high magnetic fields (B 8 T). In addition, two types of carriers are extracted from the nonlinear Hall resistance measurements, which are attributed to the Bi2Se3 bulk electrons and the electron accumulation layer at the surface or Bi2Se3/SiO2 interface, respectively. The conductivity fluctuations in the accumulation layer are believed to be the origin for the observation of positive MR in the perpendicular fields and negative MR in the parallel fields with linear and non-saturating characteristics. Published by AIP Publishing.